Protective helmet



FIG. 1 is a left side view of the protective helmet showing our new design;

FIG. 2 is a right side view of the protective helmet;

FIG. 3 is a front view of the protective helmet;

FIG. 4 is a back view of the protective helmet;

FIG. 5 is a top view of the protective helmet; and

FIG. 6 is a bottom view of the protective helmet. 

The ornamental design for a protective helmet, as shown. 